In the past 14 days, no state has seen a bigger increase in COVID-19 infections than South Dakota, where there’s been a 113% rise.

It’s difficult to untangle a single, dominant cause of the spike among many likely culprits; the state trails the national average in vaccination rates and the highly transmissible delta variant has caused case numbers to soar wherever there’s a low level of inoculation.

And then there’s the 81st Sturgis Motorcycle Rally, which was held from August 6th to the 15th. The local sheriff said it was the busiest rendition of the event in his 31-year tenure. It typically draws upwards of 500,000 people.

The rally was held mostly outdoors. Other large, open-air events have been able to operate safely. Chicago’s Lollapalooza, for example, drew 100,000 people but the city’s top doctor said there’s no evidence to link it to an increase in COVID-19 infections.

But whereas Lollapalooza attendees had to be vaccinated or provide proof of a recent negative COVID-19 test, Sturgis eschewed those precautions. On the first day of the event, NPR reportedthe rally has no vaccination, testing or masking requirements as people ride outdoors but also gather at tattoo parlors, bars, campsites and packed concerts.”

The Washington Post reports that more than 100 coronavirus infections have been linked to the event.

Health officials in South Dakota, where the rally was held from Aug. 6 to Aug. 15, said contact tracing has connected 16 cases to the event. North Dakota identified 42 cases, while Wyoming confirmed 32, Wisconsin tallied 20 and Minnesota counted 13.

The 123 cases among the five states almost certainly represent an undercount because the rally concluded less than two weeks ago and contact tracing is challenging in connection with an event that lures attendees from around the country.

Now, 1 in 3 COVID-19 tests administered in Meade, the South Dakota county that hosted Sturgis, are coming back positive. That’s a sky-high rate (it’s 11.1% nationwide.)

The Daily Beast notes that cases numbers are soaring in the counties surrounding Meade, too – “ranging from a 1,900 percent increase in the past three weeks in Butte to a 1,050 percent increase in Lawrence.”

COVID-19 deaths remain low in the area, but that metric often trails an increase in infections.

Kurra told The Daily Beast, “We knew this was going to happen. It happened last year. It was just playing a reboot of last year pretty much.”

A study co-authored by the Centers for Disease Control and Prevention found that the 2020 Sturgis Motorcycle Rally led to widespread transmission of COVID. “Although the number of cases identified is sizable — 140 cases per 100,000 attendees — it is likely that the true national impact of the Sturgis event is underestimated,” the report read.

At that rally, T-shirts were sold reading, “Screw COVID — I went to Sturgis.”